Search queries on Microsoft's Bing in the U.S. last month increased by 1%, a slow start to what a company manager predicted would be a big boost delivered by Windows 10.

According to comScore, Bing grew its share of the U.S. desktop search market from 20.4% in July to 20.6% in August. Meanwhile, the volume of search queries run on Bing increased 1% to 3.63 billion in August.

Google remained the U.S. search leader by a large margin, with a share of 63.8% -- down the 0.2 percentage points that Bing gained -- but with a search query total nearly identical to July. It was Yahoo and Ask.com that posted lower search query numbers in August compared to the month before.

But it was the 1% query increase in Bing that was notable, and not in a good way for Microsoft.

In late July, David Pann, the general manager of the Bing Ads group, told online advertisers that Microsoft expected a 10% to 15% jump in Bing's search queries by September because of Windows 10. The 1% gain of August was a poor start.

Data: comScore.

Bing needs a big boost in search queries this month if it's to meet the goal of a Microsoft manager, who bet that Windows 10 would provide a shot in Bing's arm.

The Redmond, Wash., company is banking on revenue from its Bing search engine to replace money lost as Windows license sales fall. Bing is the default search engine in Edge, the default browser of Windows 10, and is used by other components of the OS, including the virtual assistant Cortana, and central to the Cortana apps for iOS and Android.

"We're estimating query volume gains from 10 to 15 percent as early as September — not only from new users, but from existing Bing users who will now use Bing more frequently," Pann wrote on a late-July blog. Microsoft yanked Pann's post after SearchEngineLand.com reported on his comments, perhaps because it decided it did not want to be held to his numbers.

While Pann was probably predicting global gains in Bing search queries, and comScore tracks only those originating from the U.S., the fact is that Windows 10 has an even higher usage share of desktop operating systems domestically than it does overseas.

Irish analytics vendor StatCounter pegged Windows 10's average usage share over the last seven days at 9% in the U.S. but a lower 7.5% worldwide. It's unlikely that the lower usage share worldwide generated a larger increase in Bing queries than in the U.S., where Windows 10's usage is appreciably higher.

Usage share as measured by StatCounter is an indicator of online activity; it tallies web page views, then breaks them down by operating system and browser into percentages of the whole.

Bing's very slow start to what Pann believed would be a jump in Bing queries was probably due to Edge's lackluster appeal to Windows 10 users.

Even though Edge is Windows 10's default browser, even though Microsoft went to great lengths to make it so -- switching users from previous choices when they upgraded from Windows 7 or Windows 8.1 -- and even though it has adopted tactics long used by rivals to pitch Edge in Bing search results, the new browser has failed to catch on.

Another metrics firm, U.S.-based Net Applications, put Edge's user share -- a different measurement based on unique visitors -- at 39% for August.

In neither case did Edge account for a majority share among Windows 10 users. (By comparison, Internet Explorer, which in January will be relegated to a legacy support spot in Windows 10, was run by 57% of all Windows users in August, according to Net Applications.)

To make Pann's prediction of a 10% to 15% increase in search queries over July, Bing will have to jump to between 3.96 billion and 4.14 billion U.S. queries in September. (In August, Bing generated 3.63 billion queries.) Those numbers would represent a U.S. share between 22.4% and 23.4%, a 2- to 3-percentage point jump over July.